package api;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import lombok.SneakyThrows;
import model.Article;
import util.AppVar;
import util.DBUtils;
import util.ResultUtils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

/**
 * 所有文章的列表页
 */
@WebServlet("/artlist")
public class ArticleListServlet extends HttpServlet {
    @SneakyThrows
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        List<Article> data = new ArrayList<>();
        String msg = "未知错误";
        //得到前端参数并效验
        String currPage = req.getParameter("cp");
        String pageSize = req.getParameter("ps");
        int cp = 1;//当前页
        int ps = 3;//每页显示最大条数
        if(!StrUtil.isBlank(currPage)){
            cp = Integer.valueOf(currPage);
        }
        if(!StrUtil.isBlank(pageSize)){
            ps = Integer.valueOf(pageSize);
        }

        //使用分页查询，查询数据库得到数据
        Connection connection = DBUtils.getConnection();
        String sql = "select * from article order by aid desc limit ? offset ?";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setInt(1,ps);
        statement.setInt(2,(cp - 1) * ps);
        ResultSet resultSet = statement.executeQuery();
        while ((resultSet.next())){
            Article article = new Article();
            article.setAid(resultSet.getInt("aid"));
            article.setTitle(resultSet.getString("title"));
            String ctime = resultSet.getString("createtime");
            article.setCreatetime(ctime.substring(0,ctime.lastIndexOf(".")));
            String context = resultSet.getString("context");
            context = context.replace("#","");
            int maxSize = Integer.min(50,context.length());
            article.setDesc(context.substring(0,maxSize));
            data.add(article);
        }
        msg = "";
        DBUtils.close(resultSet,statement,connection);

        //将数据返回给前端
        resp.setContentType(AppVar.RESPONSE_CONTENTTYPE_JSON);
        resp.getWriter().println(JSONUtil.toJsonStr(ResultUtils.toResult(200,data,msg)));
    }
}
